Association between baseline tumour burden and outcome in patients with cancer treated with next-generation immunoncology agents

Baseline tumour burden is a prognostic factor for patients with melanoma and non-small-cell lung cancer treated with immunotherapy. However, no data are available on its role in other solid tumours, nor for treatment with next-generation immunoncology agents (NGIOs).We reviewed data of patients with any solid tumour consecutively treated at our institution from August 2014 to March 2019, who received ≥1 dose of immune checkpoint inhibitor and/or NGIO within phase 1 trials. Baseline tumour burden was calculated as ∑i Response Evaluation Criteria in Solid Tumours 1.1 baseline target lesions (baseline tumour size [BTS]) or as sum of all measurable baseline lesions (total tumour burden [TTB]); the impact of both parameters on treatment outcomes was investigated.One hundred fifty patients were included in the analysis. Median BTS and TTB were 79 mm and 212 mm, respectively. Objective response rate was found significantly associated with BTS (p 0.001) and TTB quartiles (p = 0.006), with response rates progressively increasing with decreasing tumour burden quartiles. Both progression-free survival (PFS) (p = 0.001) and overall survival (OS) (p 0.001) were significantly associated with BTS quartiles, with 26% of the patients progression-free and 56% alive at 12 months in the lower BTS quartile, compared with 3% and 24%, respectively, in the upper quartile. TTB was also significantly associated with OS (P = 0.01) and borderline-significant for PFS (p = 0.07). Multivariate analysis confirmed that baseline burden, also considered as continuous variable, is independently associated with PFS and OS, when assessed with BTS (p = 0.001 and p 0.001) and TTB (p = 0.007 and p 0.001).Lower baseline tumour burden is associated with better outcomes in patients with cancer treated with novel immunotherapies.